Which statement best describes the cost of dynamic array resizing compared to linked list growth?

• A. Dynamic array resizing may cause occasional O(n) copies; linked list with tail pointer avoids this issue.
• B. Dynamic arrays have O(n) per insertion always; linked list has O(1) per insertion.
• C. Both have identical amortized costs.
• D. Linked list appends always require O(n) time.

Answer: (A)

Dynamic array growth incurs occasional expensive copies when it runs out of capacity. When you append and the array is full, you must allocate a larger array and copy all existing elements into it, which takes O(n) time for n elements. In contrast, a linked list grows by creating a new node and linking it in, and if you keep a tail pointer, appending is simply updating the last node’s next pointer and the tail reference, which is O(1) time and doesn’t involve copying existing elements. This combination is why the statement notes that dynamic array resizing may cause occasional O(n) copies, while a linked list with a tail pointer avoids this issue. The other options misstate the costs: dynamic arrays don’t incur O(n) per insertion all the time, and a linked list with a tail pointer doesn’t always require O(n) time for appends, though without a tail pointer it could.